1. Field of the Invention
The present invention relates generally to medical implants and, more particularly, to resorbable membranes and methods of using the membranes.
2. Description of Related Art
A major clinical problem relating to surgical repair or inflammatory disease is adhesion which occurs during the initial phases of the healing process after surgery or disease. Adhesion is a condition which involves the formation of abnormal tissue linkages. These linkages can, for example, impair bodily function, produce infertility, obstruct the intestines and other portions of the gastrointestinal tract (bowel obstruction) and produce general discomfort, e.g. pelvic pain. The condition can in some instances be life threatening. The most common form of adhesion occurs after surgery as a result of surgical interventions, although adhesion may occur as a result of other processes or events such as pelvic inflammatory disease, mechanical injury, radiation treatment and the presence of foreign material.
Various attempts have been made to prevent postoperative adhesions. For example, the use of peritoneal lavage, heparinized solutions, procoagulants, modification of surgical techniques such as the use of microscopic or laparoscopic surgical techniques, the elimination of talc from surgical gloves, the use of smaller sutures and the use of physical barriers (membranes, gels or solutions) aiming to minimize apposition of serosal surfaces, have all been attempted. Unfortunately, very limited success has been seen with these methods. Barrier materials, in various forms such as membranes and viscous intraperitoneal solutions, which are designed to limit tissue apposition, have also met with limited success. These barrier materials can include cellulosic barriers, polytetrafluoroethylene materials, and dextran solutions.
U.S. Pat. No. 5,795,584 to Tokahura et al. discloses anti-adhesion or scar tissue reduction films or membranes, and U.S. Pat. No. 6,136,333 to Cohn et al. discloses similar structures. In the Tokahura et al. patent, a bioabsorbable polymer is copolymerized with a suitable carbonate and then formed into a non-porous single layer adhesion barrier such as a film. In the Cohn et al. patent, a polymeric hydrogel for anti-adhesion is formed without crosslinking by using urethane chemistry. Both of these patents involved relatively complex chemical formulas and/or reactions resulting in particular structures for use as surgical adhesion barriers. There continues to be a need to for an improved membrane.